The turn-on/off of lighting devices of a vehicle are controlled as follows: Upon user's operating a switch in a compartment of the vehicle, an input signal corresponding to the operation is inputted to an engine control unit (ECU); and the ECU controls the turn-on and turn-off of the lighting devices by turning on/off a relay according to the input signal. Patent Literature 1 describes a main ECU and an auxiliary ECU used for lighting devices, with these ECUs used to control the turn-on and turn-off of the lighting devices.